Control system



R; E. HELLMUND.

CONTROL SYSTEM.

APPLICATION FILED m4. 5. 1915.

1,349,376, Patented Aug. 10, 1920.

4 SHEETS-SHEET I.

WITNESSES :NvENToR fiado/fi. Hal/munai ATTORNEY R. E. HELLMUND.

CONTROL SYSTEM. APPLICATION FILED JAN. 5, l9l6.

Patented Aug. 10, 1920.

4 SHEETS-SHEET 2.

increase $3 so f 7/ 84 4 I as $3 M jnv. I 5rd ETNESSES lNVENTORFado/flffiel/mand ATTORNEY R. E. HELLMUND.

CONTROL SYSTEM. APPLICATION FILED JAN. 5, I916.

Patented Aug. 10,1920.

4 SHEETSSHEET 3.

ATTORNEY R. E. HELLMUND. CONTROL SYSTEM. APPLICATION FILED mms, 1916.

1 349, 37 6, Patented Aug. 10, 1920.

4 SHEETS-SHEET 4.

109 Sfd.

WITNESSES INVENTOR i the vehicle wheels that are associated with uponactuated in accordance with the primary UNITED STATES PATENT OFFICE.

RUDOLF E. HELLMUN D, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WJETING-HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATIGN 01' Pm SYLVANIA.

CONTROL SYSTEM.

Specification of Letters Patent.

Application filed January 5, 1916.. Serial No. 70,437.

To aZZ wi'wm it may concern Be it lrnown that I, RUDOLF E, HELLMUND, asubject of the Emperor of Germany,

resident of Pittsburgh, in State at en? lily invention relates toelectrically-pro polled vehicles and to systems of control therefor andespecially to vehicles that are riven by a plurality of inductionmotors.

One object of my invention is to provide, connection with a system ofthe above indicated character, means which shall be relatively simpleand inexpensive in construction and effective and reliable in operaticnfor automatically performing predeten mined functions to restore normalconditions when any set of driving wheels slips,

rapidly rotates without gripping tending to maintain normal speedcondil'n the prior art, when the acceleration of plurality of drivinginduction motors has either partially or wholly dependent the action ofa limit switch that is current of the induction motor or motors,difficulties have been experienced whenever any of the motors havestarted to slip. Under such circumstances, the primary current of theslipping motor decreases to a relatively low Value, whereby the limitswitch remains in its lower position to effect the gradualshort-circuiting of the corresponding rotor or secondary-circuitresistance, in accordance with the usual function of the limit switch;whereas, in order to eliminate the slippage, the rotor-circuitresistance of the corresponding induction m0- tor should be increaseduntil the speed of the motor has decreased to its normalvalue, inaccordance with familiar principles.

According to my present invention, I provide electrical relay means thatare electriing delta-connected secondary or cally connected with therotors of the several driving induction motors and are adaptedcounter-balance each other under norneetr con ns is a diagrammatic viewof electric loco- HlOtlVE unit embodying a plurality of driving motorsto which my invention may be applied; Fig. 2 is a diagrammatic view ofthe main circuits of a system of control embodying my 'ent' F mnticview, lowing the details or tion of the apparatus 'ti'iat -c shown inFig. 2; Fig. at is a diagrammatic view of an auxiliary governing ystemfor manipulating the circuits of I? 2- under predetermined conditions;and r 'nd. Fig. {i are diagrammatic views, t a spend to of va *iousmodifi-o' the parts of my invention. Referring to Fig. 1, the structurecomprises a locomotive cab l which ably supported upon a plurality ofartic lated trucks 2 and 3 of suitable design and which respectivelyembody a plurality of driving wheels 4: and 5, that are adapted toPatented Aug. 10, 1920.

run upon rails 6, in accordance with Lu ual Referring now to Fi 2, thesysteni shown comprises a plurality of, suitable three-chasesupply-circuit conductors A, B and C the driving induction motors M1 andM2 that may respectively comprise delta-connectul primary windings P1and P2 and cooperatrotor windings S1 and S2; a plurality of suitablevariable accelerating resistors LRl and LE2 for the rotor windings SIand S2 respectively; a plurality of main-circuit. switches LS1,

I LS2 and LS3 for connecting the primary piping system tilt coil 23 isdeenergized to the cylinder 18 and, to

- the cylinder a plurality of suitable immersible plates or electrodes12, as is customary; and lower compartments 13 from which theelectrolyte may be pumped into the tanks 11 and to which the electrolytemay be returned in accordance with the action of suitable regulating anddischarge valves 14 that are more fully described in ace-pendingapplication of A. J. Hall, Serial No. 87 3,919, filed Nov. 25, 191t, andassigned to the Westinghouse Electric 8: Manufacturing Company.lnasmuchas the-particular type of rheostat and the structural detailsthereof are immaterial to my present invention, 1 do not deem itnecessary to describe the same any further."

The electrodes or plates 12 of the rheostat Llnv1'are respectivelyconnected to the terminals of the secondary ductors 15, 16 and 17, andthe electrodes of the-other rheostat LE2 are similarly connected to thesecondary winding S2.

The operating mechanism for each of the valves 14, whereby electrolyteis admitted to the tank 11 to gradually decrease the rotor circuitresistance or is discharged from the tank 11 to the compartment 13 toincrease such resistance, comprises a suitable operating cylinder 18within which travels a piston member by a rod 20 to the movable memberof the valve 14; a valve 21 for admitting fluid pressure beneath thepiston 19 to aid in effecting the admission of electrolyte to the tank11; a second valve 22 for normally admitting fluid pressure to thecylinder 18 above the piston 19; a plurality of actuating coils 23 and24 for the valves 21' and 22, respectively; and a suitablefluid-pressure 25 for conveying fluid under pressure to the respectivevalves under predetermined cionditions.

The valve 21 is normally closed and the to prevent the access of fluidpressure directly connect the portion of the cylinder 18 that lies belowthe piston 19 with the atmosphere. Such a valve Will hereinafter bereferred to as standard valve. The other valve 22 is normally open andthe coil 24: is deenergiaed, to admit fluid pressure to 18 above thepiston 19, and only when the coil 2 1 is energized is fluid winding S1by con ing devices 19 that is secured inclusive; the actuating rea erspressure exhausted from the cylinder 18 through the valve 22 to theatmosphere. The valve just described will hereinafter be designated asan inverted valve. The actuating coils of the valves 21 and 22respectively correspond to the actuating coils 26 and 27 of the ocrating mechanism of the other rheostat L 2.

The electrical relay lneans that here comrise the auxiliary inductionmotors AM1 and AM2 are more clearly structurally illustrated in Fig. 3.The auxiliary induction motors respectively comprise stators 30 and 31,and squirrel-cage rotors 32 and 33 that are rigidly mounted upon asuitable shaft 3 1 the ends of which are carried in suitable bearings 35and 36 that are respectively supported by pedestals or brackets 37 and38.

The stators 30 and 31 are severally provided with suitable phasewindings 39 and withbearings 10 on the shaft 34,'whereby the stators mayrotatively move within predetermined limits, as about to be described,under certain torque conditions. The stators 30 and 31 are respectivelyprovided with switching devices 4'1 and 42, here shown as being of. theface-plate type, that. may be biased to positions marked D61 crease bymeans of suitable springs 13, and, in these positions the devicesrespectively rest against stops or pins 14: and 16 that are suitablyassociated .with any stationary member, such as pro'ections of thebearing brackets 37 and 38, ii desired. The switch- 11 and 12 are alsoseverally adapted to occupy second positions marked Increase when thestators 30 and 31 are .actuated as far as second stops or pins45 and 47,respectively, under predetermined lot operating conditions to bedescribed later.

The terminals of the stator winding of the auxiliary induction motorAli/l1 are connected to the respective terminals of the secondarywinding S1 by conductors t8, t9 and 50, and the stator windin of theother auxiliary induction motor A. 2 is similarly as sociated with theother. main secondary Winding S2. i

Referring to Fig; 4, the auxiliary govern-- ing system shown comprisesthe actuating co1ls of the several switches LS1" to LS6,

coils 23 to 27, inclusive, of the liquid rheostats LRI and L132 thecontact members of the switching 12a devices 41 and 42; and, inaddition,- a lurality of indicating means 1M1 and 2, that may compriselamps,bells or the like, and are preferably disposed near a trainoperator so that he may readily notice the in dications without turningaway from his regular work; a pluralit of actuating coils marked Sand-1and and-2 for actuating rail-sanding devices of the type to be describedin connection with Fig. 5; a suitable master controller MC havin fourpositions respectively marked ii, Increase, Hold and Decrease and asuitable source of energy, such as a battery B, for energizing thevarious actuating coils and indicating means in accordance with theposition of the master controller MC and the switching devices 41 and42.

Assuming that it is desired to effect operation of the system that isshown in Fig. 2, the master controller MO may be moved to its finaloperative position Decrease, wheres; a circuit is established from thepositive terminal of the battery B, through c l control fingers 56 and57, idged by contact segment 58 controller, conductor 59, the ctedactuating coils of the to LS6, inclusive, and conand 61 to the negativebattery 1, thereby connecting the primary of the driving motors M1 andM52 e sup iy-circuit conductors.

iits are established from the rent 58 of the master controller controlfingers 62 and 6-3. A ciruletcd from control Zinger 62, ouctcr 64, contct member E5 ig device in its se, conductor 36, the actuthe standardmagnet valve LE2, and cond ctcr 67 to uctcr 61. A ier circuit rated fromthe in er 63,

coil of i. he rl ostzv LE1 and conducive conductor 61. The

i F contac segment 58 also engages control 7 1 at this time, whereby onecircuit is cor pieted through conductor contact her 76 of the switchingdevice ii 2, cond ctor T, the actuating coil. 27 of the r verteo m redoctor to the negative conductor 61. A further circuit is comcleted tromcontrol finger "r, through conductor 78, conta t member Y9 of theswitching device i1, conduct-or 80, actuating coil 24 of the inverted.valve 252 of the rheostat LE1 and conductor 72 to the negative conductor61. The operating mechanisms of the liquid rheo- 131521 and LE2 willthus be actuated upwardly to gradually admit electrolyte to the tanks.11 and thereby gradually reduce the secondary resistance of therespective motors as their speed increases, in accordance with familiarpractice. To arrest the movement of the operating mechanism atany time,it is merely necessary to actuate the master controller to itsintermediate position Hold, whereby the contact segment58 is disengagedfrom control fingers 73 and 74; and the actuating coils 27 and 2% liquidrheostats'LRl and L132 alve of the rheostat LE2 and of the two invertedvalves are deenergized, so that balanced pressure conditions obtain onopposite sides of the pistons 19. In order to effect the discharge ofelectrolyte from the tanks 11 and thus increase the rotor-. circuitresistances, the master controller may be actuated to its positionIncrease, whereby all of the actuatio coils of the are deenergized, andthe pistons 19 are returned to the 7t positions shown in the drawin Itwill be understood that, in lieu of the manually-operated governingsystem just described, the familiar automatic system wherein theactuating coils 24 and 27 of the inverted valves are energized anddenergized in accordance with the position of a limit switch that hasits actuating coii connected in the primary circuit of the maininduction motors, may he empioyed, if desired.

Assuming that the wheels i that are associated with the driving motorMI. L, so that the primary current in the winding P1 is relatively low,while the speed of the 9G rotor winding Si is relatively high and itsfrequency iow, the rotor 32 of the auxiliary induction motor AM willtend to rotate at a tower speed that corresponds to the decreased speedof the rotating field in the stator 30. However, such decreased speedwiil be prevented, at least partially, by the normal action of themechanically associated rotor 33 of the other auxiliary induction motortending to drive the rotor oveasynchronousiy, so that a reactivegenerator torque is exerted upon the stator i y the stator rotativelymoves in a counterclockwise direction until the switching device 41strikes the stop 4-5 and th switching device occupies its position.increase,

As result, an auxiliary circuit (see Fig,

i} is completed from the conductor 69, through contact member 81 of theswitch- 1.16?

device 41-1, conductor 82, indicating means 1M1 and conductor 83 to thetive conductor 61. Simultaneously, the contact member 81 is connected toconductor 84:, whence circuit is completed through the actuating coilsSand-1 and conductor to the negative conductor 61.

It wiil he observed that the movement of the switching device 41 firstde'energizes the actuating coils 23 and 2 1 of the liquid rheostat LE1,whereby the electrolyte is discharged through the valve 14 to thecompartment 13, or, in other words, the resistance in the circuit of therotor winding SR1 is increased until the speed of the rotor Si hasdecreased to normal value, when the generator torque of the auxiliaryinduction motor AMl disappears and the normal ice 'motor torque,assisted by the spring 43,.

sition shown in'the drawing. ,The moveor cable 104 that passes over apulley 105 ment of the switching device 41 to its posiand has a suitablecounterbalancing weight tion Increase, likewise energizes the in-- 106attached to its outer end. A pair of dicating means 1M1 and theactuating coil standard magnet valves 107 and 108 are asof therail-sanding device, whereby the sociated with the respective ends ofthe .70 train-operator may be notified whenever any cylinder 101 foradmitting fluid pressure of the wheels are slipping and whereby the tothe one or the other side ofthe piston rails may be sanded, as morefully set forth 102 in accordance with the energization of in'connectionwith Fig. 5. It will be underthe respective valve magnets.The other stood that anyone of the three functions liquid rheostat LE2is provided with a simiperformed by the switching device 41 may lar pairof operating 7 valve magnets 109 be omitted, if desired; for example,the and 110.

Y automatic increase of the rotor-circuit re- The sanding device SD maycomprise a sistance may be omitted, and, upon the ener-' suitable hopper111, an appropriate valve gization of the indicating means 1M1, themember 112 that is associated with the core so train operatormaysuitably manipulate a member 113 of the actuating coil Sand-1 mastercontroller to manually effect the deand a suitable pipe or tube 114 forconvey-- sired increase of rotor-circuit resistance and ing .the sand tothe rails 6 in front of the thus eliminate theslippage of the motor M1.wheels 4. a v

It will be understood that, in case the Assuming that it is desired toeffect acas motor M2 and the corresponding wheels are celeration of thedriving motors, the slipping, the auxiliary rotor 33 and the switchesLS1 to LS6, inclusive, may be associated switching device 42 areautomaticlosed in any suitable manner and the switch cally actuated totheir position Increase, SW may be actuated to its upper positionwhereby'the circuits of the actuating coils marked Dec, standing fordecrease, as

. 26 and 27 of the liquid rheostats are opened, whereby a circuit isestablished from one I while a new circuit is completed from oonterminalof the battery B through conducductor 64, through contact member 86 oftors 120 and 121, the blade 122 of the switch the switchingdevice 42,conductor 87, indi- SW, stationary contact member 123, coneating means1M2 and conductor 88 to the ductors 124 and 125, actuating coil 107 of95 negative conductor 61. A further circuit the operating mechanism ofthe liquid rheois completed from contact member 86, stat LE1, conductor126, control fingers 127 through conductor 89, the actuating coil and128, which are bridged by contact mem- Sand-2 and conductor tothenegaber 97 of the switching device in its nortive conductor 61. malposition, Decrease, and conductors Reference may nowbehad toFig.5,where- 129, 130 and 131 to the negative battery in the systemshown comprises the supplyterminal. A parallel circuit is completedcircuit conductors A, B and C; the main from conductor throughconductor. 132, induction motors M1 and M2; the auxiliary the actuatingcoil 109 of the operating mechinduction motors AMl and Al /i2; theliquid anism of the rheostat LE2, conductor 133, we rheostats LE1 andLE2; the indicating control fingers 134 and 135, which are means 1M1 and1M2; the battery B and bridged by contact member 99 of the auxiltheswitches LS1 to LS6, inclusive, as hereiary switching device 96, andconductors inbefore described; and, in addition, a sand- 136, 137 and138 to the negative conductor ing device SD and a starting switch SW.131. in this way, the operating mechanisms e The auxiliary inductionmotors AMl and of the liquid rheostats are actuated to ad- AM2 arerespectively provided withmit electrolyte to the tanks 11 andgraduswitches 95 and 96 that are movable with ally decrease therotor-circuit resistances of the respective stators 30 and 31, withinprethe driving induction motors.

determined limits, and are provided with To effect the discharge of theelectrolyte Ma described.

airs of contact members 97 and 98 and 99 from the tanks 11, the switchSW may be and 100, respectively, for purposes to be actuated to itsother PCS-K1011, marked line. standing for increase, whereupon one c1r-The operating mechanism for each of the cuit is established from theblade 122 of the liquid rheostats LE1 and LE2 is somewhat switch SW,through stationary contact me different from. that previously describedand member 139, conductor 140, actuating coil comprises a suitableoperating cylinder 101 108 of the liquid rheostat LE1, and conducwithinwhich is disposed a piston member tor 141 to the negative conductor 130.A 102 that is associated with the rod 20 of simultaneous circuit iscompleted from the the valve 14, while a second rod 103 is seswitchblade 122 through statiqnary contact 1% cured to the opposite side ofthe piston 102 member 142, conductors .143 and 144, actuand is of a.sufficient length to extend ating coil 110 of the liquid rheostat LE2and through one end of the cylinder 101 when conductor 145 to thenegative conductor 131. the piston 102 is located at the other end'Thus, fiuid pressure is admitted above the thereof. The rod 103 isconnected to a cord pistons 102, the valves 14 are opened and theelectrolyte is tanks 11.

Assuming that the motor M1 and the corresponding n'heels slip While theswitch 5 SW occupi s its position Dec. the unbalunced generator torqueof the auxiliary induction motors wili cause the switching device 95occupy its dotted-line position acco dance with the in connectioncircuitis hatterv gers discharged from the such way. that only theindicating means that corresponds to the slipping motor is energized.

eference may nowbe had to Fig. 6,

86 wherein the system shown comprises the SW through stationary contactmember 190,

supply-circuit conductors A, B, and C; the driving induction motors M1and M2; the li uid rheostats and operating mechanisms L '1 and LE2; themain-circuit switches LS1 to LS6, inclusive; the battery B and theswitch SW; as iiiustrated in Fig. 5, and, in addition, solenoid-typerelay device R131 that is associated with the secondary windings S1 andS2, in manner to he de- SCZECECL 4 The reiay device 331 comprises anester sting coil 160 that is connected ductors 181 and t two of i of scondary W ating co-ii 163 the ductors 3.35 ac secondary member 166 leaWinoing i, s ada' Wardiy by the suitable sprin' s E) J. v m 1 a spectiiely disc uhe CQLQ' cers 16S it and stationary 1". whereby the relay T D1is to an intermediate position wherein a h contact l i device ocof continfoil w L switch Sin sectional contact T r conductors and a 1: l or menew hieostao movable circuitis established through conductor ie I 109 ofthe iiquid rhecstat LE2, conductor 18%, movabie contact member 172 ofthe lay device R131 and conductor 185% the negative conductor 181., Theresistances of the circuits of the secondary windings S1 and S2 are thusgradualiy' decreased in the manner already set forth w To effect thedischarge of electrolyte from the tanks 11, the switch SW may beactuated to its position marked Inc, whereupon one circuit is completedfrom the blade 175 of the switch SW through stationary contact member186, conductors 187 and 188, actuatingcoil 108 of the liquid rheostatLRl and conductor 189' to the negative conductor tablished fromthe'blade of the switch conductors 191 and 192, actuating coil 110 ofthe liquid rheostat LE2 and conductor 193 to the negative conductor 181,thereby efi'iecting the discharge of the electrolyte from the hit tanks11 in the same manner as described in connection with Fig. 5.

Assuming that the rotor S1 and the corresponding wheels slip, thevoltage of the secondary winding S1 decreases, thereby weakening thepull of the actuating coil 160 of the relay device R101 and thuspermitting the actuation of the relay device by the other coil 163 tothe lower position, wherein a circuit is established from one terminalof the battery B through conductor 194,,bridging contact member 171 ofthe relay device, and conductor 195 to conductor 188 and the actuatingcoil 108 of the liquid rheostat 101. The other actuating coil 107 issimultaneously denergized by he disconnection of the movable contactmember 173 of the relay device from conductors 179 and 180. Thus,the'resistance of the circuit of the rotor winding S1 is increased untilslippage conditions are eliminated. v

"@n the other hand, it the motor and the corresponding wheels slip,theactuat ing coil 163 of the relay device is weakened in its effect,whereb theother coil 160 actuates the device to t e upper position shownin the drawing, and a circuit is thus completed from the conductor 194:through bridging contact member 1'? 1 of the relay device and conductor1% to conductor 192 and the actuating coil 110 of the liquid rheostatLE2 to increase the resistance of the circuit of the secondary windingS2 until normal-speed 1 conditions ,are obtained. The upward movementor" the relay device effects the disengagement of the contact member 172and the corresponding contact fingers, whereby the other actuating coil109 of the liquid rheostat LE2 is deie'nergized to permit of the desiredactuation of the piston 102. v

lt will thus be seen that T have provided various simple and reliablemeans for automatically restoring normal conditions in case of theslippage otany driving motor and corresponding set of wheels, and forautomatically sanding the rails and indicating to a train'operator thata certain motor is slipping.

ll do not wish to be restricted to the specific circuit connections orarrangement and location of parts herein set forth, as variousmodifications thereof may be effected within the spirit and scope of myinvention. desire, therefore, that only such limitations shall beimposed as are indicated in the appended claims.

T claimas my invention:

1. In an electrically-propelled apparatus, the combination with aplurality of parallelmotors under wheel-slippage reaaare connecteddriving motors, of means dependent upon a predetermined abnormaldifierence of slippage automatically .and immediately changingconditions to eliminate said difference in the slippage.

2. In an electrically-propelled vehicle, the' combination with aplurality of driving wheels and. parallel-connected motors associatedtherewith, of electrical means associated with the several ed toautomatically restore normal conditions upon predetermined abnormalslippage'oi any wheel.

3. Tn an electrically-propelled vehicle, the combination with a'lurality of driving induction motors suitably associatedwith thevehicle wheels, of means dependent upon predetermined slippage of anywheels for automatically causing the corresponding motor to eliminatesaid slippage.

4;. In an electrically-propelled vehicle, the combination with aplurality of driving induction motors suitably associated within thevehicle wheels, of means associated with the rotors of said inductionmotors and dependent upon predetermined slippage of any'wheels forautomatically changing elec trical conditions in the corresponding rotorto eliminate said slippage. I

s 5., In an electrically-propelled vehicle, the combination with aplurality of driving induction motors suitably associated with thevehicle wheels, of means associated with the rotors of said inductionmotors and dependent upon predetermined wheels for automaticallyincreasing the corresponding rotor-circuit resistance to eliminate saidslippage.

6. Tn an electrically-propelled vehicle, the combination with aplurality or driving induction motors suitably associated with thevehicle wheels, of ciated with the rotors of said induction motors anddependent upon the variation of the corresponding rotor frequency uponpredetermined slippage of any wheels for increasing said correspondingrotor-circuit resistance to eliminate said slippage.

7. ln an electrically-propelled vehicle, the combination with aplurality of driving induction motors suitably associated with thevehicle wheels, of means dependent upon relative variations inconditions for automatically maintaining substantially equal and normalmotor speeds.

'8. in an electrically-propelled vehicle, combination with a pluralityof driving induction motors suitably associated with the vehicle wheels,of means'associated with the rotors of said induction motors anddependent upon relative variations in the speeds of said rotors underslippage conditions of motors and adaptslippage of any the speeds ofsaid the between the motors for means electrically assoy ticailyintor-circuit re the rotors under wheels for correspon W ,L eliminate 4,w Sari! induction motors y 1 j "4 with the vehicle ated by correspon lthe combine I actaated by ing he corresp the sliu anywheels minate Maidsiippage.

13 In eiect icail .ropelled vehici, combin tion In a p 4 raiity ofdriving induction suitahiy associated with the vehicle wheeis, of relaymeans having operating windings associated with the respective rotorssaid induction motors, said operating windings counterbalancing eachother under-substantially equal-speed conditions or" said rotors andbeing adapted under predetermined unequai rotor-speed conditions toproduce an unbalanced effect, and means dependent upon said unbalancingfor varying the resistance of one of the rotor circuits: v

14. In an electrically-propelled vehicle, the combination with aplurality of driving induction motors suitably associated with thevehicle wheels, of relay means having operating windings associatedwiththe respective rotors of said induction motors, said operating windingscounterbalancing each other under substantially equal-speed conditionsof said rotors and being adapted under predetermined slippage conditionsof any wheels to produce an unbalancedet'fect,

and means dependent upon said unbalanoing for increasing thecorresponding rotorcircuit resistance to eliminate said siippage. 15 Inan electrically-propelled vei the combination with plura uction motorssuita Ly M are vehicle wheels, of means lectric-shy associated 1induction actuated 4 a i m on the po e WI ependent inoreasin n i'rcuitresistance 18. in he combination a piur induction motors suitably a thevehicle wheels, a p i iary induction motors having inechanica associatedrotors and hav L their electrically connected 5 of aun 2.; 1:6 with. themain rotors and rotatively movable wit predetermined limits, wherebymovement the one or the other auxiliary stator from a normal positionoccurs only under page conditions of the corresponding v cle wheels andmain rotor, a plurality of variable resistors respectively associatedwith the main rotors, operating mechanisms for varying the respectiveresistors, and means dependent upon said auxiliary stator movement foreffecting the actuation of the one or the other operating mechanism toeliminate said slippage.

19. In an electrically-propelled vehicle,

1 varying the respective resistors,

the combination with a plurality of driving induction motors suitablyassociated with the vehicle wheels, of a plurality of auxiliaryinductionmotors having mechanically associated rotors and having their statorselectrically connected with the respective main rotors and rotativelymovable within predetermined limits, whereby movement of the one or theother auxiliary stator a normal position occurs only, under slippageconditions of the corresponding vehicle wheels and main rotor, aplurality of variable resistors respectively associated with the mainrotors, fluid-pressure-operating mechanisms for varying the respectiveresistors, electrically-controlled valves for governing the actuation ofsaid mechanismsin the one or the other direction, and switch ing meansdependent upon said auxiliary stator movement for effecting theelectrical energization of said valves in such manner as to increase therotor-circuit resistance of the proper motor to eliminate said slippage.a

20. Tn an electrically-propelled vehicle, the combination with inductionmotors suitably associated with the vehicle wheels, of relay meansassociated with the respective'rotors for producing an unbalanced effect'under slippage conditions of the corresponding vehicle wheels and mainrotor, a plurality of variable resistors respectively associated withthe main rotors, fluid-pressure operating mechanisms forelectricallycontrolled valves for governing the actuation of saidmechanisms in the one or the other direction, and switching meansdeendent upon said unbalanced action for effecting the electricalenergization of said valves in such manner as to increase therotor-circuit resistance of the proper motor to eliminate said slippage.

21. The combination with a plurality of main induction motors, of arelay device actuated in accordance with the relative speeds of saidmotors and comprising 'a plurality of auxiliary induction motorsconnected to the respective main rotors.

22. The combination with a plurality of main induction motors, of arelay device actuated in accordance with the relative speeds of saidmotors and comprising a plurality of auxiliary induction motors havingmechanically associated" rotors and severally having stator windingsconnected 'to the main rotors.

23. The combination with a plurality of main induction motors, of arelay device actuated in accordance with differences in main rotorfrequencies. v

24:. The combination with two alternating-current systems normallyoperating with a predetermined frequency ratio there between, of meansresponsive to a departure from , mechanically coupled signed a pluralityof driving reeaere from said frequency ratio comprising two inductionmachines having mechanically coupled rotors and having primary windingsconnected to said systems, respectively, said motors being designed toproduce coordinating torques with substantially no energy transfer atsaid predetermined frequency ratio, and either of said motors beingdriven hyper-synchronously by the other motor upon a decrease 1n therelative frequency of the system connected to said driven motor.

25. The combination with two/alternating-current systems normallyoperating at the same frequency, of means responsive to a departure fromsaid frequency equality comprising two induction machines having rotorsand having primary windings connected to said systems, respectively,said motors being deto produce coordinating torques with substantiallyno energy transfer with frequency, equality in said systems, and eitherof said motors being driven hyper= synchronously by the other motor uponthe frequnecy of the system connected to said driven motor beingexceeded by the frequency of the remaining system.

26. The combination with two alternating-current systems normallyoperating with a predetermined frequency ratio therebetween, of meansresponsive to a departure from said frequency ratio comprising twoinduction machines having mechanically coupled rotors and having primarywindings connected to said systems, respectively, and stator membersarranged to oscillate between stops and to effect circuit control bysaid movement, said motors being designed v to produce coordinatingtorques with sub- 1 stantially no energy transfer at said predeterminedfrequency ratio, and either of said motors being drivenhyper-synchronously by the other motor upon a decrease in the relativefrequency of the system connected to said driven motor to cause themovement of the associated stator from one stop to the other andcorresponding circuit control.

27. The combination with two alternating-current systems normallyoperating at the same frequency, of means responsive to a departure fromsaid frequency equality comprising two induction machines havingmechanically coupled rotors and having primary windings connected tosaid systems, respectively, and stator members arranged to oscillatebetweenstops and to effect circuit control by said movement, said motorsbeing designed to produce co6rdihating torques with substantially noenergy trans er with frequency equality in said systems, and either ofsaid motors being driven hyper-synchronously by. the other motor uponthe frequency of the system connected to said driven motor being ex- 130ceeded by the .frequency of the remaining system to cause the movementof the associated stator member from one stop to the other andcorresponding circuit control.

28. The combination with two alternating-current systems, of a relaydevice actuated in accordance with the relative fre quencies of saidsystems and comprising a plurality of mechanically coupled auxiliarymotors associated therewith.

29. The combination with a plurality'of alternating-current systems, ofa relay device actuated in accordance with differences in the relativefrequencies of said systems.

30. In an electrically-prepelled apparatus, the combination with aplurality of parallel-connected driving motors, of means responsive to arelatively great difference of slippage between the motors forautomatically and immediately changing conditions only until suchdifference of slip page is eliminated.

31. In an electrically-propelled vehicle, the combination with aplurality of parallel-connected driving motors suitably associated withthe vehicle wheels, of means responsive to predetermined slippage of anywheels for automatically causing the corresponding motor to eliminatesaid slippage and for maintaining continuous operation of all drivingmotors.

'32. In an electrically-propelled vehicle, the combination with aplurality of driving induction motors suitably associated with thevehicle wheels, of differential means associated with the rotors of saidinduction motors and responsive to predetermined slippage of any wheelsfor automatically changing electrical conditions in the correspondingrotor to eliminate said slippage and restore normal conditions in thevehicle.

33. In an electricallypropelled vehicle, the combination with aplurality of driving induction motors suitably associated with thevehicle wheels. of differential relay means associated with the rotorsof said induction motors and responsive to relative variations in thespeeds of said rotors under slippage conditions of any wheels forautomatically increasing the corresponding rotorcircuit resistance onlyuntil said slippage is eliminated.

In testimony whereof, I have hereunto subscribed my name this 31st dayof Dec.

RUDOLF E. HELLMUND.

